Investigation of structure and dissolution properties of a solid dispersion of lansoprazole in polyvinylpyrrolidone

The use of polyvinylpyrrolidone K30 (PVPK30), as a carrier for the treatment of acid-related disorder drugs of lansoprazole (LPZ), to prepare solid dispersions with the weight ratio 1:3 of LPZ:PVP by solvent evaporation was investigated. Differential scanning calorimetry (DSC), X-ray diffractometry (XRD), Fourier-transformed infrared spectroscopy (FT-IR), 1H Nuclear magnetic resonance (1H NMR) and high resolution atomic force microscopy (AFM·IPC-208B) was employed to elucidate the physical state of solid dispersions, molecular structure and interactions between drug and carrier, as well as dissolution behaviors of the dosage formations. The results of DSC and XRD indicated that LPZ was presented in an amorphous or molecular state in the solid dispersions and the presence of hydrogen bonding interaction between the >NH of LPZ and CO of PVPK30 in solid dispersions were confirmed by combining FT-IR, 1H NMR and AFM·IPC-208B. The amorphous state of LPZ coupled with presence of hydrogen bond between LPZ and PVPK30 was the main cause for the markedly enhancement of dissolution rate with over 80% of drug released or 26.7 times faster than that of the pure drug within 30min. These results confirmed that LPZ–PVPK30 solid dispersions prepared by the solvent evaporation could be used as a means of enhancing LPZ dissolution rates and shown than setting high resolution AFM·IPC-208B as a new device was highly beneficial for the structural investigations, providing intuitively the spatial conformation and the interactions between the drug and carrier or other systems at the molecular level.